This invention relates to a tape cartridge loader mechanism, for example, for loading a single-reel magnetic tape cartridge into a tape drive, to enable reading data from and writing data to the tape, and for unloading the cartridge from the tape drive.
Computers utilize a variety of magnetic media devices for the storage of software programs and data. Information recorded on the magnetic medium takes the form of flux transitions that represent the binary xe2x80x9c1""sxe2x80x9d and xe2x80x9c0""sxe2x80x9d that form the digital information. Tape cartridges, such as single-reel tape cartridges, are commonly used in library or other archival data storage applications. In such applications, a user or a robotic mechanism selects a tape cartridge for processing and inserts the cartridge into a tape drive coupled to a computer. In a fully automated system, a mechanism within the tape drive loads the tape from its entry point to a position in which the tape becomes accessible for read-from and write-to operations.
A variety of different size data tape cartridges are available. The drives for the different size cartridges, however, must be substantially the same size, so as to fit within a standard size slot or space available within the framework of a personal computer or the like. Larger cartridges enable storage of more data on the tape within, however, the larger the cartridge the more difficult it is to design a drive mechanism to fit within the design envelope.
For example, some single reel cartridges are 105.4 mm wide, by 102 mm long by 21.5 mm high. Such a cartridge, by itself fills a substantial portion of the design envelope for the tape drive. As a result, tape drives for this type of cartridge have utilized manual loading mechanisms. All movement and operations to load the tape cartridge into the drive, open the tape door for access to the tape leader and engage the tape drive gear to the drive motor gear have been manual in nature. A portion of the cartridge remains outside the drive, even in the fully loaded position.
Data cartridge tape drives have been developed with automatic or xe2x80x9csoftxe2x80x9d loading and unloading of the cartridge. However, because of the size and complexity of the loading mechanism, these automatic loaders have been used only in drives for smaller tape cartridges.
Also, automatic cartridge tape drives must be able to load and unload cartridges many times without jamming or other failures. A failure of an automatic loader mechanism may damage a tape cartridge and makes the drive unusable until repaired or replaced. Typical design parameters for drives available today call for the loader mechanism to continue to operate successfully for at least 300,000 loading/unloading cycles. For applications with frequent cartridge replacement, such as tape library systems providing access to volumes of data to many users via networks, to have a truly useful life each tape loader mechanism must operate successfully with little or no wear for many more cycles than even this design parameter.
Automatic loader mechanisms have been developed in the past that include some form of conveyor to retract the cartridge entirely within the drive and lower the cartridge for engagement with the tape drive motor gear. These mechanisms are motor driven and must include some means to convert the rotational motion of the motor into a complex motion of the conveyor during loading and unloading operations. The mechanisms for actuating the conveyors in such loaders have used complex linkage systems of two or more pivotal members, to achieve the necessary degrees of motion, to load and unload the cartridge. Such linkage systems take up considerable space within the design envelope of the tape drive, making it impossible to design an automatic drive for a relatively large cartridge. Also, such linkage systems are rather fragile. Such a linkage wears quickly and may be damaged by impact, either when the user inserts the cartridge with too much force or due to an external impact on the drive or computer housing.
It should, therefore, be appreciated that a need exists for an automatic loading mechanism for data tape cartridges that takes up the minimum amount of space within the design envelope of the tape drive, to allow the mechanism and the drive to handle as large a cartridge as possible. Also, a need exists for a loader mechanism of this type that is particularly durable and can operate successfully for a large number of loading/unloading cycles without any jams or other failures.
Furthermore, at least some cartridge tape drives use a magnet and a metal plate to form a magnetic clutch, to engage the cartridge gear to the drive gear associated with the motor. In an automatic loader, the loader motor must supply sufficient torque during unloading to overcome the magnetic clutch forces, in order to separate the cartridge from the cartridge drive motor. This imposes high torque and power requirements on the loader motor. To produce adequate torque typically requires a larger motor and more electrical power. The high torque also tends to wear out drive linkages quickly.
A specific need exists for a technique to reduce the torque requirement on the loader motor needed to separate the magnetic clutch elements, to allow use of a smaller motor and reduce stress and wear on loader components. However, any solution intended to reduce this torque requirement must not inordinately increase size or complexity of the loader or compromise its durability.
The present invention meets the above-stated needs and overcomes the problems with prior cartridge loader systems.
A tape cartridge loader in accord with a first aspect of the invention includes a moveable shuttle for receiving the tape cartridge and means for actuating the shuttle during loading and unloading operations. The means are adapted to occupy minimal space within the loader. Also, the actuating means require minimal motor torque, particularly during initial operation for unloading a tape cartridge.
Another aspect of the present invention relates to an automatic tape cartridge loader. The loader includes a mechanism for receiving the tape cartridge. In response to a linear actuation, the loader mechanism moves the cartridge into operative engagement with a data tape drive. The loader also includes means for applying the linear actuation to the loader mechanism.
The preferred embodiments include a number of unique elements as part of the actuating means. For example, to actuate a linear motion of the shuttle, the loader includes a rotatable actuator arm. The arm is substantially flat. The arm includes a groove at a distance from its axis of rotation. The groove edges serve as cam profiles, to drive a bearing attached to a conveyor to move the conveyor along a linear path during loading and unloading operations. The groove edges are contoured to maintain substantially 90xc2x0 contact with a circumference of the bearing, during each linear motion of the bearing and conveyor. The actuator also preferably conveyor interacts through a cam profile and follower arrangement to produce the necessary movement of the shuttle, during loading and unloading operations.
The use of the flat actuator arm and cam follower minimizes the height of the elements for converting the motive force into a linear actuation of the conveyor. Also these elements are relatively simple and durable. The selection of the cam profile contour, to maintain perpendicular force on the follower bearing provides efficient transfer of linear force, preferably to push the follower and the conveyor. The torsion spring may serve a number of different functions. If the cam profile is that used during loading, the spring biases the follower bearing into engagement with the profile and provides impact buffering between the conveyor and the actuator arm, to absorb impacts due to insertion of the tape cartridge. If the cam profile is that used in an unloading operation, the torsion spring actually helps to push the follower bearing and thus the conveyor.
Other unique elements as part of the actuating means provide simple efficient actuation of the shuttle and assist in separation of the cartridge gear from the drive gear during unloading, for example to overcome a magnetic clutch attraction between the gears. One such element relies on cam followers of different sizes attached to opposite sides of the shuttle and driven by profiles to apply different lift forces to the sides of the shuttle during unloading of a cartridge. Another element for assisting in gear separation relies on application of a load balancing spring force, to provide the assist. In the preferred implementations, two compression springs attached to a base of the loader are compressed by motion of the shuttle to the position in which the tape cartridge is loaded and the gears engage.
The assistance provided to separate the gears, either in the form of the inventive cam followers and profiles or in the form of the load balancing spring(s), reduces the torque and/or power requirement on the loader motor during the unloading operation. The loader may use a smaller motor, and the reduced torque tends to extend the useful life of the loader and motor. The relevant components take up relatively little space within the design envelope of the motor.
Another aspect of the invention relates to an automatic tape cartridge loader, for loading a tape cartridge into a tape drive for reading and writing of data on a tape within the cartridge. This loader includes a frame housing, a conveyor, an actuator arm, and a shuttle. The conveyor is mounted for linear motion within the frame housing. The conveyor has opposing first and second sidewalls, a first cam profile in the first sidewall, and a second cam profile in the second sidewall. A bearing attached to the conveyor is arranged for linear motion relative to the frame housing. The actuator arm is substantially flat and is coupled to the frame housing for rotation about a fixed axis. The arm has a groove at a distance from the axis. One or more of the edges of the groove provide substantially perpendicular cam contact to the bearing on the conveyor, during at least one rotational movement of the actuator arm. The loader includes two cam followers attached to opposing sides, which engage the profiles in the sidewalls of the conveyor. The second cam follower is larger than the first cam follower, and the cam profiles are contoured so as to apply different forces through the followers to the shuttle, during unloading of the tape cartridge. The inventive loader also includes at least one spring, for producing a force on the shuttle to assist in initial movement of the shuttle during the unloading of the tape cartridge.
Another aspect of the invention relates to a tape drive incorporating an inventive cartridge loader. The tape drive includes a tape drive motor and a tape drive gear. A magnet is secured to the tape drive gear, for attracting the gear in the tape cartridge. In this tape drive, the automatic loader includes a frame housing as well as a conveyor and attached bearing mounted for linear motion within the frame housing. A substantially flat actuator arm is coupled to the frame housing for rotation about an axis. The arm includes a groove at a distance from the axis. At least one edge of the groove provides substantially perpendicular contact to the bearing during the rotation of the actuator arm. A loader motor rotates the actuator arm, to cause the linear movements of the conveyor.
The loader of the tape drive also includes a shuttle for receiving the tape cartridge. A cam profile and cam follower arrangement couples the shuttle to the conveyor. This arrangement enables movement of the shuttle to and from a position within the loader in which the gear within the tape cartridge engages the tape drive gear, in response to the linear movements of the conveyor during loading and unloading of the tape cartridge. The loader also includes means for assisting in overcoming the attraction by the magnet and in separation of the gear within the tape cartridge from engagement with the tape drive gear.
In the preferred embodiment, the cam and profile arrangement actually includes two profiles on the conveyor and two cam followers. The profiles are formed on opposite sides of the conveyor, and the cam followers are attached to opposite sides of the shuttle. The cam followers are different sizes, and the associated cam profiles apply somewhat different forces to the sides of the shuttle during unloading. Each profile includes a first inclined section having a high pressure angle, for inducing a substantial portion of the motion of the shuttle toward cartridge-loaded position. Two compression springs provide extra lift during unloading. A second section of the profile has a low pressure angle, for inducing additional motion of the shuttle, to reach or pass the cartridge-loaded position and overcome the opposing spring force.
The preferred embodiment of the shuttle includes cantilevered springs for applying spring force toward the tape drive motor to the cartridge within the shuttle and for buffering the cartridge within the shuttle. The cam profiles induce motion of the shuttle slightly past the cartridge-loaded position, to produce a gap between a surface of the cartridge and an adjacent surface of the shuttle. The cantilevered springs buffer the cartridge within the shuttle, when the shuttle moves past the cartridge-loaded position.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.